A conventional 3-D character data generating device is disclosed, for instance, in Japanese Laid-Open Patent Application No. 63-103380, “3-D Character Generating Device”. The following describes this device as the first conventional technique with reference to FIG. 1.
A 2-D character input unit 140 inputs a 2-D character, which is stored in a storing unit 120 as a character on an x-y plane. Based on the inputted 2-D character, a 3-D character form is designed by a user's operation of a z-direction correcting unit 130. During this operation, the user views the display unit 110. A z coordinate of each point of the character is changed on an x-z projection face 112 and a y-z projection face 113 to convert the inputted 2-D character to a 3-D character. The 3-D character on which such correction is being made is displayed on a 3-D projection face 114 for viewing. An area background input unit 150 inputs image data. Based on this image data, an image is added onto the surface of the 3-D character stored in the storing unit 120, and the image-applied 3-D character is displayed on the 3-D projection face 114. In this technology, however, a 3-D character is generated not automatically but through adjustments made by the user using the x-z projection face 112 or the y-z projection face 113.
A technique aiming to generate 3-D characters automatically is disclosed, for instance, by Japanese Laid-Open Patent Application No. 11-53578, “Form Converting Method, a Recording Medium Storing a Procedure of the Converting Method, and a Form Converting Device”. With this second conventional technique, only side planes of a character are generated based on outline data representing a character form in the 2-D plane. This conventional technique therefore does not generate an entire 3-D character and only generates part of the 3-D character.
Japanese Laid-Open Patent Application No. 11-53579 discloses “Form Converting Method, a Recording Medium Storing the Conversion Procedure, and a Form Converting Device”. According to this third conventional technique, a 2-D bitmapped font character is inputted, and each set of bit data constituting the bitmapped font character is corrected to a 3-D form. The sets of bit data are then synthesized to produce the whole character in the 3-D form. Such bitmapped font character, however, is likely to have a coarse outline. It is therefore necessary to use a bitmapped font using many bits for each character so as to minimize the coarse outline of the character.
According to the first conventional technique, 3-D characters are manually generated, which increases an operator's operational load and takes a great processing time. The first conventional technique therefore cannot generate 3-D characters in real time. The second conventional technique tries to generate 3-D characters automatically, but this technique only generates data representing a side plane of a 3-D character without generating front and back planes of the character, which are important elements for 3-D character-representation. The data generated by the second conventional technique is therefore incomplete and not useful. The third conventional technique can provide 3-D characters. However, as it generates 3-D characters from bitmapped data, resulting 3-D characters have a coarse outline. When these characters are used in computer graphics (CG), outlines of these characters become coarser through the CG operation, so that the quality of the characters considerably decreases. In addition, when all the bitmapped data is converted into 3-D characters of a certain quality, a great amount of data is required.